1. Field of the Invention
This invention relates to computer architectures and, more particularly, to specialized computer control units for efficiently handling regular expression text pattern-matching.
2. Description of the Prior Art
During the initial days of general purpose digital computers, applications involved almost entirely arithmetic and control types of computation. Since that time, there has been a steady shift from such primarily arithmetic applications to a heavy dependence on symbolic computation, typified by document preparation and text searching, often as part of so-called "office automation" systems. However, the basic architecture of computers has not been dramatically affected by this change in applications. Computers remain essentially serial machines with elaborate arithmetic capabilities and therefore do not provide efficient non-numeric computation.
One movement away from this historical approach is represented by applicants' copending application, Ser. No. 177,095, filed Aug. 11, 1980. This application discloses a highly parallel computer architecture particularly suited for processing raw text streams into formatted text lines for printed documents. Large-scale integration technology has made such complex circuitry economical for heavily used applications, such as document preparation.
Another fundamental process used in office automation systems is searching through lines of text for given words, phrases, or sentences. This pattern-matching is particularly vital to locating pertinent information in large masses of textual data available in machine-readable form, i.e., in large data bases. Indeed, the well being of the information age is heavily dependent on fast and efficient methods of locating pertinent information in large collections of such information. Again, however, the traditional design of general purpose digital computers, as essentially arithmetic, serial machines, has not lent itself to fast and efficient pattern-searching. Indeed, because of the large volume of data which must be processed in a serial manner, many data retrieval problems become uneconomical; extensive indexing schemes are resorted to in order to limit the field of search.